Device in a melting or holding furnace for facilitating the charging thereof

ABSTRACT

A device in a melting or holding furnace for facilitating the charging of the furnace, said device comprising an upwardly directed charging duct ouside of the furnace and in communication with the frunace at the lower portion thereof, the charging duct at its upper end being provided with a device for stirring of the molten material in the charging duct.

United States Patent [191 Gering Feb. 5, 1974 [54] DEVICE IN A MELTING ()R HOLDING 3,343,828 9/1967 Hunt 266/33 R FU N C FOR FACILITATING m 1,674,947 6/1928 Bunce et a1. 266/33 R 2,464,714 3/1949 Petersen 266/33 R CHARGING THEREOF 3,088,182 5/1963 Tama et a1. 266/33 R [75] Inventor: Kuido Gering, Vasteras, Sweden 3,341,092 9/ i 1 2/566 3,441,261 4/1969 Sommer 266/33 R [73] Assignee: Granges-Essen AB, Vasteras,

Sweden Prima Examiner-Gerald A. Dost Fl 7, 197 [22] 1 ed June 1 Attorney, Agent, or Firm-Fred C. Philpitt [21] Appl. No.: 150,595

[30] Foreign Application Priority Data 57 ABSTRAT June 10, 1970 Sweden 8065/70 A device in a melting or holding furnace for facilitatl 266/33 266/34 34 A ing the charging of the furnace, said device comprising [5 hit. Cl. an upwardly directed charging duct uside of the fur- Fleld of Search 266/33 34 R, 34 nace and in communication with the frunace at the 29 lower portion thereof, the charging duct at its upper end being provided with a device for stirring of the References Clted molten material in the charging duct.

UNITED STATES PATENTS 2,191,337 2/1940 Clark 266/33 R 5 Claims, 1 Drawing Figure DEVICE IN A MELTING OR HOLDING FURNACE FOR FACILITATING THE CHARGING THEREOF The present invention relates to melting or holding furnaces and more particularly a device for facilitating the charging of such furnaces.

A melting or holding furnace is provided with members for supplying heat to the space in the furnace which is adapted to contain material to be melted, alloyed of held warm. The furnace is also provided with devices allowing discharge of molten material, when said material has reached the desirable condition for casting. After the discharge of a certain quantity of material the furnace is normally supplied with new material for melting by the charging of the furnace. This new material must be introduced down into the remaining melt, which at times may be difficult, especially if the new material is formed of small pieces or parts with a lower volume weight. The difficulties are further increased due to the surface tension of the melt and the layer of cinder which is generally present over the melt. This new material must then in some manner be forced down into the melt, which has up to the present been performed by manual or mechanical stirring downwards thereof. However, this work is very hard and disagreeable due to the very high temperature and the development of fumes from the melt. Further, at the melting of scrap more cinder is oftenformed on the surface of the melt, which additionally complicates the stirring of new material down into the melt.

The object of the present invention is to provide a melting or holding furnace, which can be charged automatically or at least with less severe manual work in respect of work physiology.

This object has been attained by the furnace of the invention having been given the features as claimed in claim l.

In addition to a simpler supply of charging material to the furnace, the furnace of the invention also pres ents the advantage that by closing the main space of the furnace by means of a cover or the like and providing a high pressure in the main space of the furnace above the surface of the melt, it is possible to raise the level ofthe melt in the charging duct located laterally of the main space. By raising the level in the charging duct right up to the top edge of the charging duct an extremely simple possibility is attained for discharging the cinder, which has been accumulated in the upper portion of the charging duct during the charging of the furnace and during the melting of the new material. The cinder can then be discharged or withdrawn over the edge of the charging duct. By regulating the pressure in the main space of the furnace it may also be attained that the top surface of the molten material in the charging duct is maintained at a high level, so that a stirring device located at the upper portion of the charging duct, e.g., an inductive stirring device, can operate efficiently, even if the quantity of material in the main space of the furnace is relatively small. This fact is of special importance at a low level of the melt in the furnace.

The invention will now be described more closely with reference to the accompanying drawing, which shows a cross section through an induction furnace with a charging device according to the present invention.

,The furnace 10 illustrated on the drawing, is provided with a heating device at its bottom 11 in the form of an induction coil 12 with a magnetic core 13 surrounded by a channel for molten metal. In addition, the furnace is provided with a discharge spout 14, through which molten material can be discharged by tilting the furnace around a horizontal shaft 15. The heating device at the bottom of the furnace has such dimensions that material, which has been charged into the furnace, can be maintained in a molten state both in the main space 16 of the furnace and in a charging duct 17, which is located laterally of the main space of the furnace and connected with the main space at the lower portionthereof. The charging duct 17 has the form of a tube, which extends with its top edge 18 to a level above the surface of the melt in the main space, when said main space is filled to a normal level of operation.

The upper portion of the charging duct 17 is comprised of a tubular assembly 19, which is releasably mounted on the furnace 10. During the operation of the furnace this assembly is namely exposed to heavy stress and rapid wear and, therefore, must be replaced at intervals. The assembly 19 may also be provided with an exchangable insert tube, even if not shown on the drawing. The replacable assembly comprises a coil 20, the axis of which coincides with the longitudinal axis of the charging duct 17, so as to allow inductive stirring of at least the upper portion of the melt in the charging duct, so that material supplied into the charging duct may be carried down into the melt more easily. Said coil is supplied with AC of a suitable frequency and operates on the basis of the electrodynamic force (the pinch effect). The top edge 18 of the-charging duct 17 is formed with a spout 21 for allowing the discharge of the cinder, which has been accumulated in the upper portion of the charging duct.

The main space 16 of the furnace is closed by a cover I 22, in which an aperture 23 is provided for the connection of the space 24 above the melt with a pressure source (not shown) with a controllable pressure. By regulating the pressure above the melt in the main space 116 of the furnace the level in the charging duct 17 of the furnace can be raised or lowered at will. By raising the level an extremely simple discharge of the cinder is obtained which during the melting of charging material has been accumulated in the upper portion of the charging duct. In addition, by means of a simple increase of the pressure of the pressure source the level in the charging duct can be maintained so high that the inductive stirring device 20 is in full action at all times. By the connection of the main space of the furnace with a special pressure source the advantage is also attained that it is possible to operate with a special atmosphere in the main space of the furnace, e.g., an atmosphere without oxygen, whereby the formation of cinder on the surface of the melt in the main space of the furnace is substantially reduced.

The furnace illustrated on the drawing is a so-called channel furnace, a channel 25 being provided, wherein molten metal is accumulated and heated, when the furnace is in operation. This channel forms a closed secondary winding around the magnetic core 13, which is located in the induction coil. For the operation of the furnace this channel must always be filled with electrically conducting material, e.g., a metal. A certain residual quantity of the melt must thus always be left in the furnace so that it can be started again. The level of the ity of the inductive stirring device for stirring the melt in the charging duct, so that the newly supplied material is easily ca'rried downwards into the melt and thereby is more rapidly molten." I

The heat supply to the'charging' duct should be of such a value that small pieces or small parts fed into the charging duct are molte'n at least in respect of their surface layer during the transport of .the parts down into the melt, before they ajreach the {,point'at which the charging ductt'urns'so.i'asto' openinto the main space of the furnace; Bye-such, aevalrls theadvantage is attained that all the cinder which 'is'formedat the melting of such parts will be, accumulated on the surface of the melt in the chargingdut'and is notintroduced into the main space of the, furnace As mentioned aboire ijli furnace shown is of the channel type but is tunder s'tood that the present invention may be appliedin -a furnace of any type. Further, only one heating device'has been shown but it is evident that a pluralityof such heating devices may be arranged, either of the inductivetype or of any other type, along the bottom ofthefurnace or at an other suitable location in gonnec tionwith the main space of the furnace. It is onlyof importance thata sufficient quantity of heat is supplied to' the mainspace and the charging duct of the furnace. The discharge of the-melt 2i A furnace as set forth in claim 1 in which the inductive" stirring device comprises a coil positioned from the main space of the furnace may, of course, also be perfon'ned in many other ways than through a discharge channel of the type shown on the drawing and if required a plurality of charging ducts may be provided.

I claim: 1. A melting or holding furnace having an improved charging means, said furnace comprising a. a main space having heating means located in the lower portion thereof for melting, alloying or warm holding of a quantity of material contained therein, b. at least one vertically extending charging duct located externally of said main space, 0. the lower portion of said main space being in communication with the lower end of each said charging duct, d.'the upper portion of each said charging duct being providedwith inductive stirring means for stirring the material charged thereto and moving same downwardly toward said main space.

aroundfeach charging duct at the upper portion thereof and adapted to be supplied with AC for producing a varying electro-magnetic field in the charging duct.

3i A furnace as set forth in claim 1 wherein the upper portion of each charging duct in releasably mounted on the furnace so that it. can be replaced after excessive wear.

4. A furnace as set forth in claim 3 wherein the charging duct istprovided with a replaceable insert tube.

5.-,A furnace according to claim 1 wherein said main space is provided with a cover and an aperture adapted to be connected to a pressure source. 

1. A melting or holding furnace having an improved charging means, said furnace comprising a. a main space having heating means located in the lower portion thereof for melting, alloying or warm holding of a quantity of material contained therein, b. at least one vertically extending charging duct located externally of said main space, c. the lower portion of said main space being in communication with the lower end of each said charging duct, d. the upper portion of each said charging duct being provided with inductive stirring means for stirring the material charged thereto and moving same downwardly toward said main space.
 2. A furnace as set forth in claim 1 in which the inductive stirring device comprises a coil positioned around each charging duct at the upper portion thereof and adapted to be supplied with AC for producing a varying electro-magnetic field in the charging duct.
 3. A furnace as set forth in claim 1 wherein the upper portion of each charging duct in releasably mounted on the furnace so that it can be replaced after excessive wear.
 4. A furnace as set forth in claim 3 wherein the charging duct is provided with a replaceable insert tube.
 5. A furnace according to claim 1 wherein said main space is provided with a cover and an aperture adapted to be connected to a pressure source. 